Pneumatic action for pianos and similar musical instruments.



A.J.HOBART. PNEUMATIC LOTION FOB PIANOS AND SIMILAR MUSICAL INSTRUMENTS.

APPLICATION FILED IAIN. 31, 1910.

Patented Mar-.7, 1911.

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PNEUMATIC ACTION FOB PIANCS AND SIMILAR MUSICAL INSTRUMENTS.

986,288. Patented M11127; 1911.

APPLICATION FILED JAN. 31, 1910'.

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ADAM J'. HOBART, OF ST. JOHNSVILLE, NEW YORK, ASSIGNOR '10 F. ENGELI-IARDT &

' SONS, OF ST. JOHNSVILLE, NEW YORK.

PNEUMATIC ACTION FOR PIANOS AND SIMILAR MUSICAL INSTRUMENTS.

Specification of Letters Patent.

Patented Mar. *7, 1911.

To all whom it may concern:

Be it known that I, ADAM J. Honan r, a citizen of the United States, residing at St. Johnsville, county of lVIontgomery, State of New York, have invented new and useful Improvements in Pneumatic Actions for Pianos and Similar Musical Instruments, of which the following is a specification.

This invention relates to an improved construction of the pneumatic action which is controlled by a music sheet and actuates the hammers of a piano or similar musical instrument. The action is compact, simple in construction, and effectively checks leakage at the valves, so that a reliable transmission is obtained, while waste of power is avoided.

In the accon'ipanying drawings: Figure 1. is a front view of part of my improved pneumatic action, showing the same applied to the piano hammer actuating means; Fig. 2 a plan of Fig. 1, with some of the parts omitted; Fig. 3 a vertical transverse section on line 33, Fig. 1, and Fig. at an enlarged transverse section on line 4.'-l, Fig. 2.

My improved pneumatic action comprises a pair of superposed valve boxes or blocks 10 and 11, extending preferably across the entire width of the piano and arranged in front of the lifters that actuate the piano hammers. Near its ends, lower block 10 is supported upon the flanges 12 of the upright main vacuum pipes 13, while upper block 11 is spaced from block 10 by a pair of intermediate stays 11, one end section only of the blocks bein shown in the drawing. As the lower sides of blocks 10 and 11 are beveled for the attachment of the action bellows 15 and 16, respectively, triangular fillers 1'7 are interposed between block 10 and flanges 12, and between block 11 and stays 1 1, all these parts being firmly united by thumb-screws 18, as illustrated in Fig. 3. Bellows 15 are adapted to actuate alternate hammers of the piano, while bellows 16, that stagger with bellows 15, are adapted to actuate the hammers located intermediate those first mentioned. For this purpose, the movable board of each bellows is provided with a tappet 19 extending below the cushioned head of a screw 20 which engages a bracket 21 secured to lifter The latter aotuates its hammer through wippen 23, in the usual manner.

For collapsing bellows 15 and 16, each block 10 and 11 is provided with a pair of vacuum chambers 24:, 25, from which the air is constantly withdrawn through pipes 13 and upright channels 26 formed in fillers 17 and stays 14. As the lower block 10 1s a duplicate of upper block 11, the invention may be understood by confining the description to the upper block.

For each bellows 16 there is provided a primary valve and a secondary valve, which valves are controlled by a perforation in the music sheet, as usual. The primary valve consists of a longitudinally fluted stem 27 guided in a pair of bushings 28 fitted into a correspondingbore 29 of block 11 and carrying a pair of valve-disks 30, 31 cushioned as at 32. Bushings 28 are preferably provided with flanges 33, the outer diameters of which are smaller than those of cushions 32, so that the edges of the latter extend beyond those of the former. In this way the frequently, more or less, rough rims of the cushions do not contact with the valve seats, so that undue leakage is avoided, while, for the same reason, the valvedisks are not liable to stick to their seats. Into the lower end of stem 27 is screwed a button 31 which is provided with peripheral notches 35 for the engagement with a suitable gripping tool, so that by turning the button, its distance from valvedisk 31 may be adjusted. Button 31- rests upon a diaphragm 36 secured to the bottom of chamber 24:. Below the diaphragm, block 11 is provided with a shallow recess 37 that permits a slight sagging of the diaphragm.

The stem 38 of the secondary valve which is alined with the stem of the primary valve transversely to the wind chest of the instrument is guided in a pair of perforated bars 39, of which one is secured to a longitudinal rail 40 supported by block 11, while the other is arranged within vacuum chamber 25. Stem 38 carries a pair of cushioned valve-disks 41, 12, playing in a chamber =13 and adapted to engage flanged bushings 1-4. The latter are fitted into corresponding bores of block 11. and rail t0, the diameters of disks 11 exceeding those of bushings sat, for the reasons above given. To the bottom of stem 38 is secured a button resting upon a diaphragm 46 which is secured to the bottom of vacuum chamber 25 below said button, block 11 being provided with a shallow recess 47 for accommodating said diaphragm.

The perforated music record controls, in the usual manner, by means of a tracker bar (not shown), a flexible tube is for the pneumatic action for each of the piano hammers. Tube 48 ecn'nnunicates with a pipe 49 inserted into a front flange 67 of a board 50 which is secured to block 11. Pipe Q9 opens into a port 51 of flange (37 which communiates through an angular duct 52 with recess 37, said duct being also connected with vacuum chamber 2-ithrough a bleed hole 53. I prefer to interpose between port 51 and duct 5'2, a wire netting 511: which retains all dust or other solid particles entering through tube s8. Netting 5-l and port 51 may be readily cleaned by removing a button 55 which normally closes said port. Bore 29 communicates through a passage 56 with recess N, while chamber a?) is, by duct 57 and opening 58 of bellows 16, connected with the interior of said bellows. For adjusting the stroke of the movable board of bellows 10, the latter is provided with a cushion 59 which is adapted to be engaged by the cushioned head of a screw 60 tapped into block 11 and passing through duct 57 and opening 58.

In order to deaden the sound of the upper primary and secondary valves, I prefer to secure to block 11 and rail s0, above said valves, a pair of inverted U-shaped hoods 61, 2 which are open at both ends to permit free access of air. The sound of the lower valves is prevented from diffusing by a longitudinal upright plate 63 arranged intermediate boards 50.

The air inlet ports of lower board 50 are, by pipes 64: and flexible tubes 65 connected to the lower protruding ends of pipes (36 extending through the upright perforations of flange (57, said perforations being formed in said flange intermediate ports The upper ends of pipes (36 are by flexible tubes 48, connected to the tracker bar of the instrument.

The operation of the device will be readily understood. The uncovering of any perforation of the tracker bar admits air below the diaphragm 56 of the corresponding primary valve, so that the latter will ascend to admit air through passage 56 below diaphragm 46 of the secondary valve. The latter will thus also rise to connect the cooperating action bellows with vacuum chamber 25. The bellows will thus collapse to raise l tappet 19, which will, in turn, raise lifter 22 to actuate the piano hammer. After the perforation in the tracker bar has again been covered by an imperforate section of the music record, the air will be withdrawn through bleed hole 53 from the recess below diaph agin 36, so that the primary and secondary valves will descend to permit the expansion of the action bellows.

\Vith instruments of the class described in which the pneumatic action is located in the forward part of the arse, it is of importance that the depth of the action be reduced to the greatest extent possible, in order to notunduly enlarge the dimensions of the case. lVith a tier construction of valve blocks, it is obvious that the connections between the primary valves of the lower tier and the tracker bar are obstructed by the valve block of the upper tier, so that without further means, it would be necessary to locate said lower valve connections in front of the upper block. By applicants device this waste of space is entirely obviated and the upper valve block is utilized not only for the purpose of receiving the pipe connections of the upper tier, but also for sustaining and accommodating the pipe connections for the lower tier which are interposed between the inlet ducts of the upper tier, so that in this way the proper co-relation of the parts is maintained.

I claim:

A device of the character described, comprising an upper block having a front flange and a plurality of ports and upright perforations extending alternately through said flange, a lower block, a plurality of primary and secondary valve chambers in each block, means for maintaining the blocks at a distance from each other, a first set of air inlet pipes fitted into the upper block flange and connnunicating with the ports of said flange, a second set of pipes fitted into the perforations of the flange, a third set. of pipes fitted into the lower block, and tubes connecting the second set of pipes with the third set of pipes, the pipes of the first and third sets communicating respectively with the primary valve chambers of the upper and lower blocks.

ADAM J. HOBART.

\Vitnesses \VALTER L. INGELHARDT, ALxxsoN C. HaUeH'roN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

